Handheld audiometric device and method of testing hearing

ABSTRACT

Handheld apparatus ( 100 ), and method for comprehensive hearing testing with pass/refer results applicable for large scale neonatal screening, adult screening, full hearing diagnostic is disclosed. The apparatus ( 100 ) contains a signal processor ( 1 ), integral ear probe ( 150 ), and remote ear, and scalp probes ( 104 ) all packaged as a single handheld battery operated device ( 100 ). The apparatus ( 100 ) preferably performs a battery of tests, either independently or combined: oto-acoustic measurements utilizing a novel digital signal processing method for evoked oto-acoustic signal processing, auditory brain stem response test, tympanometry, and oto-reflectance. Algorithms for automatic test sequence, and pass/refer indication for the tests are provided.

This application claims of U.S. Provisional Ser. No. 60/131,542, filedApr. 29, 1999.

TECHNICAL FIELD

This invention relates to the field of auditory measurement devices andassociated screening methods. In particular, the invention relates to ahand-held auditory measurement device, which has features beneficial toall neonatal screening programs. While the invention is described withparticular emphasis to its auditory screening application, those skilledin the art will recognize the wider applicability of the inventiveprinciples disclosed hereinafter.

BACKGROUND ART

Universal neonatal auditory screening programs have expanded greatlybecause of improved auditory measurement capability, improvedrehabilitation strategies, increased awareness of the dramatic benefitsof early intervention for hearing impaired babies and changes ingovernmental policies. Current neonatal auditory screening approaches,however, do not account adequately for the many different types anddegrees of auditory abnormalities that are encountered with presentscreening approaches. Because of this, individual screening tests basedon a single measurement can be influenced negatively by interactionamong various independent auditory abnormalities. Current screeningapproaches have not considered adequately the entire screening programincluding (i) physical characteristics of the measurement device i.e.,portability, physical size and ease of use, (ii) operationalcharacteristics of the device i.e., battery life, amount of recordstorage, required operating training, etc. and/or (iii) programlogistics i.e., retesting mechanisms, referral mechanisms recordprocessing, patient tracking, report writing, and other practicalaspects. These factors can interact negatively to increase the totalcost of an auditory screening program including the primary economiccost of screening, testing, the secondary economic cost of additionaltesting, and non-economic costs such as parental anxiety incurred whenprovided with incorrect information.

These costs, both actual and human, can be reduced by reducing the costper test, reducing the false positive rate, and resolving false positivescreening results at the bedside prior to hospital, discharge. The costper screening can be reduced with a dedicated device optimized forscreening in any location and enhanced to allow effective operation byminimally trained personnel. The performance characteristic of thedevice of our invention includes reduced measurement time, the abilityto operate and configure without an external computer, the ability tointegrate and interpret all test results, the ability to store largenumber of test results, long battery life, and bi-directional wirelesstransfer of data to and from external devices.

We have found false positive results can be reduced in two ways. First,the initial screening test performance can be improved with enhancedsignal processing, more efficient test parameters, and by combiningdifferent types of tests. Second, false positive rates also can bereduced by providing a mechanism for resolving an initial screening testfailure at the bedside at the time of the initial screening. Thiscapability is provided through the availability of an automatedscreening auditory brainstem response (ABR) test capability provided bythe same device. Secondly, operational processes of a screening programcan be improved through the use of several onboard computer based expertsystems. These computer based expert systems provide improved automaticinterpretation of single test results, automatic interpretation ofmultiple test results, and improved referral processes through thematching of local referral sources with various test outcomes, such as areferral to a specific type of follow-up, whether it be a pediatrician,audiologist, otolaryngologist, or a nurse. The device disclosedhereinafter integrates in a single, hand-held device, a single stimulustransducer, a single processor and a single software application forotoacoustic emission (OAE). ABR testing, tympanometry andotoreflectance, as well as OAE simulator.

An auditory abnormality is not a single, clearly defined entity with asingle cause, a single referral source and a single interventionstrategy. The peripheral auditory system has three separate divisions,the external ear, the middle ear, and the sensorineural portionconsisting of the inner ear or cochlea and the eight cranial nerve.Abnormalities can and do exist independently in all three divisions andthese individual abnormalities require different intervention andtreatment. Prior art physical and operational characteristics of devicesand their influences on program logistics can interact negatively toincrease the total cost of an auditory screening program. The primaryeconomic cost is the cost of each screening test though this is not theonly economic cost. A screening test failure is called a “refer” andusually is resolved with an expensive full diagnostic test scheduledseveral weeks after hospital discharge, resulting in significanteconomic cost. A substantial portion of these costs is unnecessary ifthe screening false positive rate is high. Non economic costs includeparental anxiety for false positive screening results, unfavorableprofessional perception of program effectiveness for programs with highfalse positive rates and even inappropriate professional interventionbecause of misleading screening results.

The intervention of multiple measurements into a single hand-heldinstrument allows for very important new functionality not availablewith existing neonatal auditory screening devices. This functionalityincludes (1) detection of common external and middle ear abnormalities;(2) the detection of less common sensorineural hearing loss associatedwith outer hair cell abnormalities, and (3) the detection of even lesscommon sensorineural hearing loss associated with inner hair cell orauditory nerve abnormality. Moreover, the device disclosed hereinafterhas the potential to improve the accuracy and reliability of OAEmeasurements, to allow for optimal interpretation of both the OAE andABR results, and to improve the referral process.

Attempts have been made in the past to provide the capabilities providedby the present invention. In particular. U.S. Pat. Nos. 5,601,091 ('091)and 5,916,174 ('174) disclose audio screening apparatus which purport toprovide a hand-held portable screening device. However, the screeningdevice disclosed in those patents is used in conjunction with aconventional computer, and requires a docking station for fullapplicational use. In no way does the disclosure of either patentprovide a hand-held device that can be used independently of any othercomputer. That is to say, the invention disclosed hereinafter provides adevice of significantly reduced size i.e. hand-held, which is capable ofproviding OAE and ABR testing, as well as tympanometry otoreflectance,and OAE simulator. It can be operated in a stand-alone mode,independently of any other computer connection, if desired. The deviceincludes a patient database, with names, and full graphic displaycapability. The device also preferably is provided with a wirelessinfrared and an RS 232 connection port to provide output directly toprinters or to a larger database where such is required.

The '174 and '091 patents also operate on a linear averaging method toremove background noise. While such method works well for its intendedpurposes, use of a linear averaging method is time consuming.Consequently, we developed a frame overlap method for rejecting noiseand improving signal reliability in a device which measures, in theembodiment illustrated, 7¼″×3 ¾″×1½″.

SUMMARY OF INVENTION

One of the objects of this invention is to provide a reduced sizehand-held device for auditory screening which provides OAE, ABR,tympanometry, otoreflectance and OAE simulator operation.

Another object of this invention is to provide an audio screeningdevice, which is hand-held and operates in a fully stand-alone mode,operating independently of any other computer connection.

Another object of this invention is to provide a hand-held device thatprovides a patient database on the device.

Another objection of this invention is to provide a hand-held audioscreening apparatus that provides for full graphic display on the deviceitself.

Another object of this invention is to provide a device that increasesnoise rejection and reduces processing time through the use of frameoverlapping techniques.

A further object of this invention is to provide a device with ABRtesting that automates electrode impedance checking prior to test.

Another object of this invention is to provide a device which is low incost, and which can be adapted to provide a wide ranging of auditoryscreening applications.

In accordance with this invention, generally stated, an effectiveauditory screening method and device are provided. The integration of anOAE screening device and ABR screening device into a single, hand-heldinstrument enables a user to detect less common sensorineural hearingloss associated with outer hair cell abnormalities and the detection ofless common sensor hearing loss associated with inner hair cellabnormalities. In the preferred embodiment, the device includes aportable hand-held enclosure containing a digital signal processor. Theprocessor has a computer program associated with it, capable ofconducting both otoacoustic emission test procedures and auditorybrainstem response test procedures for a test subject. A display deviceis mounted to the enclosure, and displays patient information, testsetup procedure, and test results including graphing of test results.The enclosure includes a connection point for a probe, the connectionpoint being operatively connected to the signal processor. The devicealso includes an onboard power supply, making the device completely selfcontained.

A method of testing OAE response in a test subject is provided whichutilize a unique method of noise reduction to provide acceptable dataeven in high level ambient noise conditions of the test subject'senvironment.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, FIG. 1 is a top plan view of one illustrativeembodiment of audio screen device of the present invention.

FIG. 2 is a view in end elevation;

FIG. 3 is a view in end elevation of the end opposite to that shown inFIG. 2

FIG. 4 is a block diagrammatic view of the device shown in FIG. 1;

FIGS. 5 and 6 are block diagrammatic views of the algorithm employedwith the device of FIG. 1 in connection with ABR testing;

FIG. 7 is a diagrammatic view of frame sliding implemented by thealgorithm of FIG. 4; and

FIG. 8 is a block diagrammatic view of the algorithm implemented withrespect to OAE testing to improve the signal to noise ratio employedwith the device of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

The following detailed description illustrates the invention by way ofexample and not by way of limitation. This description will clearlyenable one skilled in the art to make and use the invention, anddescribes several embodiments, adaptations, variations, alternatives anduses of the invention, including what we presently believe is the bestmode for carrying out the invention. It will nevertheless be understoodthat no limitation in the scope of the invention is thereby intended,and that alterations and further modifications of the illustrativedevices is contemplated, including but not limited to furtherapplications of the principles of the invention illustrated herein aswould normally occur to one skilled in the art to which this inventionrelates.

Referring now to FIGS. 1–3, reference numeral 100 illustrates oneembodiment of the audio screening device of the present invention. Thescreening device 100 includes an enclosure 102, which in the preferredembodiment, and for purposes of illustration and not for limitation,measures 7¼″ long by 3¾″ wide by 1½″ deep. It is important to note thatthe device 100 can be carried by the user without compromise, and trulyrepresents a portable hand-held device having full functionality asdescribed below. The device 100 includes a keyboard 5, an LCD display 4,an LED pass/refer indicator 7, and an LED AC charging indicator 17.Again, by way of illustration and not by limitation, it should be notedthat the screen 4 measures, in the preferred embodiment, approximately2″ by 3⅜″. The measurement is not necessarily important, except to showthat the LCD display is fully functional for a user, and the unit canoperate independently of any other computer system. In the embodimentillustrated, the enclosure 102 also houses an infrared port 18, acompatible RS-232 port 18 a, a probe connection 90 for an ear probe 150,and an interface 103 for a plurality of electrodes 104. The electrodes104 are shown attached to a conventional carrier 151.

Ear probe 150 is conventional and is not described in detail. Suitableprobes are commercially available from Etymotic Research, Part No.ER-10C, for example.

A novel feature of this invention is the provision of an OAE simulatorear probe interface 160. The simulator function permits a user to testthe integrity of the entire OAE test system, by providing activefeedback and simulation of a test subject's ear.

Referring now to FIG. 4, a block diagram view of the device 100 is shownand described. The device 100 contains OAE, ABR and OAE simulatorcapabilities in a single, hand-held package. Preferably, the systemshown in FIG. 4 is manufactured on a single printed circuit board, withmixed signal design for both analog and digital operation. The devicepreferably is low powered, and generally operates at 3.3 volts, exceptfor the LCD 4 and some low power portions of the analog circuitryemployed with the device 100.

A digital signal processor 1 is the control for the device 100. In thepreferred embodiment illustrated, the processor 1 is a Motorola chip DSP56303. All signal processing functions described hereinafter areperformed by the processor 1, as well as the control of all input andoutput functions of the device 100. In addition, the graphic functions,user interface, patient data storage functions and other devicefunctionality are controlled by the processor 1. In conventional designlogic, the digital signal processor 1 is used for signal processing, anda separate micro controller is used for device control. We have beenable to eliminate the separate microprocessor, resulting in substantialsavings in space, cost and power consumption.

A memory subsystem 2 is operatively connected to the processor 1. Thememory subsystem 2 includes a random access memory 2 a for storingintermediate results and holding temporary variably an a flash memory 2b for storing non-volatile, electrically programmable variables, patientdata and configuration information. In the embodiment illustrated, theflash memory 2 b is substantially oversized, enable the device 100 toaccommodate as many as 300 full patient records, as well as multipleconfigurations files.

A memory mapped input/output device 3 is operatively connected to thememory subsystem 2 and to the digital signal processor 1. The memorymapped input/output 3 in turn is operatively connected to the LCDdisplay 4, the keyboard 5, the pass/referral LED indicator 7 and a realtime clock 6.

The LCD display 4 is the largest non-custom LCD available. While customLCD displays can be obtained, they add prohibitive cost to the product.The LCD display 4 provides the user with 128×256 pixels of graphics.That display is sufficient to present full waveforms of audiometrictests conducted by the device 100. The keyboard 5 preferably is amembrane switch keyboard, which incorporates only the minimum keysnecessary for operation of the device 100. All keys are programmable,except for the on/off key 105.

A real time clock 6 is operatively connected to the processor 1 throughthe memory mapped device 3. The clock 6 enables the processor 1 toprovide a time stamp for each patient and test performed, as well asproviding time signals for internal operation of the device 100.

The LED pass/refer diode 7 is used to convey test results to non-trainedusers, namely a nurse as opposed to an audiologist or otolaryngologist.Use of the LED 7 avoids confusion or misinterpretation of the LCDgraphics display 4, and allows use of the device 100 in low light areas,where the LCD display 4 may be difficult to interpret.

The plurality of analog to digital/digital to analog coder/decoders 8(codecs 8) is operatively connected to the signal processor 1. As willbe appreciated by those skilled in the art, the codecs 8 are specialintegrated circuit chips that perform analog to digital and digital toanalog conversion. The codecs 8 are operatively connected to the signalprocessor 1 along a dedicated serial link indicated by the referencenumeral 107. The codecs 8 in turn are operatively associated with aplurality of input/output devices, which provide the functionality ofthe device 100 under control of the processor 1.

An otoacoustic emission interface 9 is operatively connected to thesignal processor 1 through the associated codecs 8. The interface 9preferably is a low noise, differential analog circuit with high commonmode noise rejection. The interface 9 is intended to drive two soundtransducers inserted in the ear canal which produce a variety ofsignals, from pure tones at various frequencies to chirps, clicks, sinewaveforms etc. The otoacoustic emission interface 9 can present tones atall standard audiometric frequencies and sound pressure levels. Thedevice employed with the interface 9 includes a microphone, alsoinserted in the ear canal, which collects signals coming back from theear, and provides sufficient linear amplification to present the signalsto the codecs 8. In various embodiments of this invention, the interface9 also can be used for otoreflectance measurements for assessing somemiddle ear conditions.

The ARB interface 10 consists of a plurality of analog signal processingchips, not shown individually, which filter and amplify the signalsconnected from the scalp of a subject via electrode wires 104. In thismode of operation, the ear is presented with a repeated auditorystimulus, which causes firing of the eighth nerve, and the associatednerve, pass Into the brainstem. As those firings occur, electricalpotentials are generated all the way to the scalp, and there they aredetected by the electrodes 104. An additional function of the interface10 is to provide automated impedance check of the placement ofelectrodes. Once the electrodes are in place, a small current is,injected through the electrodes into the scalp of the subject, and theimpedance between electrodes is measured. Impedance can be varied byplacement of the electrodes. Once the impedance is within apredetermined range for operation, ABR signal connection can begin. Itis important to note that impedance checking can be accomplished withoutunplugging the electrodes. That is to say checking is automatic. Aslater described in greater detail, the measured ABR response is based onthe detection of a peak in the waveform in a point approximately up to15 milliseconds after a sound click, depending upon gestational age orpatient age. The actual latency of this peak is then compared to thelatency of this peak in normal hearing neonates or adults.

The otoacoustic emission simulator interface 11 is used to check theintegrity of the OAE system. It includes a transducer or speaker and amicrophone. The microphone collects the signals presented by the OAEprobe, presents them to the codecs 8 and processor 1 for signalprocessing, and then the speaker presents the corresponding tone at thecorrect frequency and amplitude back to the original OAE probe thusproviding an active, calibrated test cavity.

Our invention optionally may include a tympanometry interface 11 a inplace of the interface 11. The tympanometry interface 11 a comprises anelectronic output channel to drive a miniature pump, not shown, whichcan produce pressure or a vacuum in the ear canal of a test subject. Acorresponding pressure sensor is used to measure this pressure, and thesignal from the pressure sensor is fed into an analog input of thecodecs 8. The signal can be used as an independent feature, and thedevice will show full graphics output on the LCD 4 in real time. In thealternative, this test may be used in combination with the OAE or ABRtest to compensate for middle ear conditions.

A mode configuration system 12, a reset watchdog system 13, a crystalclock 14, a power supply 15 and a battery charger 16 all are alsopositioned within the enclosure 102 and operatively connected to theprocessor 1. While each of these blocks is required for operation of thedevice 102, they are standard in nature and are not described in detail.

The processor 1 has an input output channel 18, which are preferably aninfrared connection and an isolated RS-232 interface. The device 100 cancommunicate with any infrared compatible or RS-232 compatible personalcomputer, printer, or other digital device for data transmission. Datatransmission may include patient information, configuration data for thesignal processor 1, or software program updates.

A buzzer 19 also is provided. The buzzer 19 provides an audio feedbackto the user for keyboard actions and audio indication for errorconditions.

A serial port 20 also is operative connected to the processor 1. Theserial port 20 is utilized to provide direct programming of theprocessor 1 from a personal computer, for example, and is intended foruse only for initial software download and major software programupgrades of the processor 1.

A distortion product otoacoustic emission (DPOAE) is a tone generated bya normal ear in response to the application of two external tones. Whentwo tones, f₁ and f₂ are applied to an ear, the normal non-linear outerhair cells generate a third tone f_(dp), which is called a distortionproduct. F_(dp) then propagates from the outer hair cells back to theear canal where it is emitted. The level of the DPOAE can be used as ameasure of outer hair cell function. If the outer hair cell system isabsent or otherwise not functioning properly, the non-linearity will beabsent or reduced and the f_(dp) will either not be generated orgenerated at a lower than expected level.

The measured DPOAE is highly dependent upon the specific tones thatinvoke it. The frequencies of f₁ and f₂, and their respective levels inthe ear canal, L1 and L2 must be controlled precisely. Under knownsignal conditions, the largest distortion product is generated at a veryspecific frequency (f_(dp)=2 f₁−f₂), and level L_(dp). Comparison of thelevel of L_(dp) with known values from individuals with normal outerhair cell systems forms the basis of the decision of whether the patienteither passed the screening (pass/refer LED 7) or requires a referralfor a more complete diagnostic testing.

Signals other than pure tones can be presented to the ear, which willalso evoke a response from the ear, such as clicks, chirps, etc. DPOAEis used to as an example, the other stimuli would be processed the sameway.

The processor 1 utilizes a unique method of detecting signals for theOAE test. While the method is a time domain sum and average operation,the key concept is to reuse data from adjacent frames to average withthe current frame. This method is described for the purpose of thisspecification as “sliding”. The limit to the size of the overlap is theauto correlation of original data. The method works on the assumptionthat the data within the overlap frames is different, and that the noiseis uncorrelated. It is key to keep the frame size an integer number (oneor more) of the original data cycles.

The important difference between the method of the present invention andlinear averaging is that the overlapping number M (sum operation) equals((frame number divided by (frame size minus 1)) times (frame sizedivided by (frame data cycle length plus 1))) which is larger than thereceived data frame number by a factor by which the previous frame isslid. Therefore, the expected performance of this method is better thanstandard linear averaging. In this method, the frame size divided byframe data cycle length must be an integer. The method is showndiagrammatically in FIG. 5 and FIG. 6.

The processor 1 algorithm is implemented and explained with reference toFIG. 7 and FIG. 8. As there shown, the processor 1 sends an outputthrough, the digital analog converter portion of the codecs 8 throughthe OAE interface 9 to the ear probe, utilized in conjunction with thedevice 100. The ear probe includes a microphone which returns signalsthrough the interface 9 and the codecs 8 to a new frame buffer 111 inthe processor 1. The size of the new frame buffer 111 is calculated tobe an integer number of samples of the two primary tones at frequenciesf1 and f2, and also, an integer number of samples of the otoacoustictone produced by the ear at f_(dp). This is a critical step to assurequality of subsequent signal processing, by avoiding windowingtechniques, which can introduce substantial artifacts. Tables of numbersfor each standard frequency employed in the device 100 and for otherfrequencies in use or intended for use in the device 100 are available,and are programmed into the algorithm once the user selects the testfrequencies. Should a combination of frequencies by required for whichno common integer number can be found to fit in a practical size frame,the frame size is adjusted to f_(dp) and the frame is windowed prior toFourier Transformation, but this method is used only in extreme casessince in normal operation, the required frequencies are available.

The data from the single frame is passed to a point Discrete FourierTransform 112 (DFT) block which calculates the signal's magnitude andphase content, but only at frequencies of interest, including f₁, f₂,f_(dp) to determine a noise floor. Windowing is induced prior to DFT toreduce edge effects, although windowing induces energy at other bands.The block 112 is used only for temporary calculations, and the windoweddata is not reused again. The output of block 112 is the magnitude andphase of primary signals at f₁ and f₂ and the noise floor figure of timeat f_(dp). The output of block 112 forms an input to frame rejectionblock 113 and to an on-line calibration calculation block 114.

With the information on the magnitudes at various frequencies, a noisecalculation algorithm is employed at and around f_(dp) to determine thenoise floor. The magnitude of the noise floor and frequency content areused against a set of predetermined conditions i.e. a comparison againstan empirically derived table contained in the processor 1, to determinethe outcome of the frame. That outcome has three distinct possibilities.First, if the noise magnitude and frame content exceed a multi-thresholdcondition at measured frequency bands, the new frame is rejected.Second, if the noise magnitudes fall between a set of reject thresholdsand a set of accept thresholds, the data in the frame is disregarded,but the noise information is kept to update the noise level average.

Third, if the noise magnitudes are below the accept thresholds, theframe is kept and passed on for further processing and the noisemagnitudes are averaged together with the noise average of the previousframe. This information is used to update thresholds, such that thesystem adapts to environmental conditions.

When the information about magnitudes of primary tones at f, and f₂, andthe noise floor information at and around f_(dp), an online calibrationof the level of magnitudes takes place. Several actions occur in thecalibration block 114. First, if the noise floor is large when noprimary tones are present, the frequency of the primaries is adjustedwithin predetermined limits. A new f_(dp) is calculated, and the noisecontent of frequency bins at and around f_(dp) is checked again. Thisprocess is repeated until a stable, low noise floor is established. Noprimary tones are played through the speaker through this process. Oncethe primaries are presented, they are stepped up to the full outputamplitude, as programmed by the user and calibrated in the ear byincreasing the output of the codecs 8. No data collection from the earhas taken place yet. At this time, if the level is not reached in a userpredetermined time, and at the rate of increase of the primaries, thetest is aborted due to lack of fit or the low quality of fit of theprobe in the ear canal. Once the proper fit is achieved, and testingbegins, data collection takes place. During the entire process of datacollection, the levels of tones at f, and f₂ are checked to ensure thatthey remain within predetermined limits throughout the test. If theyexceed those limits, the output is adjusted up or down to compensateuntil a maximum compensation limit is reached, at which time, the testis aborted and the user is notified. Also, the magnitude at and aroundf_(dp) is continuously monitored to assure low noise floor, and ifnecessary, the frequency of the primary tones are adjusted on-linewithin predetermined limits to avoid the high external noise region. Thechange in frequencies of the primaries is minimal, and within thespecified tolerances of the device 100, and have been shown not toaffect the magnitude of the tone within the car at f_(dp).

The block 115 is a store/copy buffer. As a frame is collected in newframe buffer 111, a copy of it is saved for processing of the subsequentframes.

The buffer 115 receives frame data from new frame buffer 111. The storeand copy frame buffer 115 has a variable depth, depending the number offrames averaged together. Buffer 115 provides an output to a block 116and a block 17. The block 116 operates with the stored previous frames,which are slid by a predetermined amount and the empty spaces paddedwith zeros for subsequent processing in the averaging old and new frameblock 117.

In block 117, the frames are averaged together to reduce theuncorrelated noise present. Theoretically, the noise is reduced by afactor of one over the square root of the number of averaged frames. Theframes are averaged in a linear fashion, sample by sample and a newframe is created at the end of the averaging operation. The advantage ofthis method is that the data is essentially correlated against a slidcopy of itself, slid far enough away to avoid averaging the sameinformation content. This provides either a substantial reduction inuncorrelated noise energy for the same amount of sampling time or asubstantial reduction in sampling time to obtain the equivalent noisereduction when compared to standard linear averaging.

The minimum limit to the sliding of the data, and to the reuse of olddata frame is the autocorrelation function of the data in the frame,which can be predetermined or calculated on-line. This method isequivalent to taking much smaller frames and averaging them together.However, for the purposes of the subsequent Fourier Transformations andfiltering taking place, the frame size is required to be large (i.e.,960 samples at 48 kilohertz sampling rate), to obtain several fullcycles of each of the tones at f1, f2 and f_(dp). The problem withtaking a large number of very small frames is that the FourierTransforms or other signal processing methods require several cycles ofdata for proper operation. The method of the present inventionoutperforms standard linear averaging of large frames because of thereduction in time as well as providing proper operation of the FourierTransforms.

The block 118 obtains the averaged data from the block 117, and collectsit in a buffer that is used for subsequent processing and signalstatistics. The output of the block 118 is digitally filtered in theblock 119. The filter 119 removes any remaining high or low frequencycomponents not required for final data presentation.

The averaged and filtered data is converted to frequency domain, in theembodiment illustrated, by using a discrete Fourier Transform in theblock 120, and the data then is ready for presentation in block 121. Aswill be appreciated by those skilled in the art, other signal processingmethods are available to convert data, and those other methods arecompatible with the device 100.

As indicated above, the device 100 enables the LCD 4 to presentinformation to a user graphically in real time on the device itself,complemented with textual and numeric information about the quality ofthe fit, amplitudes, frequency, noise floors and other relatedinformation.

Operation of the device for ABR testing is shown in FIG. 5 and FIG. 6.In ABR testing, the magnitude of the fifth peak is the one that is ofprimary interest, and the device 100 determines the magnitude of thefifth peak by counting zero crossings, after substantial filtering anddigital preprocessing. As shown in FIG. 5 and FIG. 6, the systemproceeds to count zero crossings and stores an index of an array elementupon determination of a zero crossing. If additional zero crossings arerequired, the procedure is, repeated until the fifth peak is determined.Upon detection, the single waveform is isolated, and the waveform peakis correlated to find the maximum correlation sinusoid. Thereafter, thedevice 100 determines the time of occurrence of the fifth peak and thatvalue is checked against empirical data to obtain proper correlation.

Numerous variations, within the scope of the appended claims, will beapparent to those skilled in the art in light of the foregoingdescription and accompanying drawings. For example, the design of theenclosure may vary in other embodiments of the invention. Likewise, LCDdisplay 4 may be replaced with other display devices. As indicated inthe specification, we use a discrete Fourier Transform to obtain datafor display. Other signal processing methods are compatible with thebroader aspects of the invention. These variations are merelyillustrative.

1. An auditory screening device, comprising: a portable hand-heldenclosure; a signal processor housed by said enclosure, said signalprocessor configured with a computer program operated on command by auser to produce one or more auditory tests and associated stimulussignals selected from a group comprising otoacoustic auditory emissiontest procedures, auditory brainstem response test procedures,tympanometry, and otoreflectance for a test subject; a memory modulehoused by said hand-held enclosure, said memory module operativelyconnected to said signal processor and configured to maintain at leastone test subject record; a display device mounted to said enclosure,said display device being operatively connected to said signal processorfor displaying results of a selected auditory test in real time; a probeconnection point on said enclosure, said probe connection point beingoperatively connected to said signal processor; a power supply; andwherein said signal processor is configured to perform a time domain sumand average over time for detecting otoacoustic auditory emissionsignals using an offset frame overlap method.
 2. An auditory screeningdevice, comprising: a portable hand-held enclosure; a signal processorhoused by said enclosure, said signal processor having a computerprogram operated on command by a user, said program configured toproduce auditory tests selected from a group comprising otoacousticemission test procedures, auditory brainstem response test procedures,tympanometry, otoreflectance, and combinations thereof for a testsubject; a display device mounted to said enclosure, said display devicebeing operatively connected to said signal processor, said displaydevice displaying the results of the selected test in real time; a probeconnection point on said enclosure, said probe connection point beingoperatively connected to said signal processor; and a power supply foroperating the signal processor; wherein said signal processor isconfigured to perform a time domain sum and average over time forotoacoustic emission test signal detection, using a frame overlapmethod; and wherein said auditory screening device further comprises amemory subsystem that includes provisions for patient data.
 3. Thedevice of claim 2 wherein an auditory brainstem test signal isdetermined by digital signal processing and counting zero crossings ofcorrelated internally generated sinusoids.
 4. A method of conducting anotoacoustic auditory emission audio test, comprising the steps of:inserting a probe in a patient's ear, said probe including a speaker anda microphone; connecting said probe to a hand-held device; generating anauditory signal in said hand-held device, detecting incoming auditorysignals generated in said ear via said microphone; converting saidincoming auditory signals to digital signal data; storing said incomingdigital signal data in a new frame buffer; sizing said new frame bufferto be an integer number of samples of two primary tones at frequenciesf₁ and f₂ and an integer number of samples of a tone produced by saidear at frequency f_(dp); passing digital signal data from a single frameto a discrete Fourier transform process to calculate a frequencyspecific magnitude and phase content of said incoming auditory signalsignal; comparing said calculated magnitude and phase to a table todetermine whether to reject the digital signal data, to discard thedigital signal data but update a noise table; or to save the digitalsignal data; collecting said digital signal data until a predeterminednumber of frames have been saved; averaging said digital signal dataover a predetermined number of sequential frames, wherein data fromsequentially preceding frames is slid by a predetermined number of datapoints prior to said averaging; converting said averaged data to afrequency domain; and displaying said averaged frequency domain data tothe user in a hand-held device in real time.
 5. The method of claim 4further including the step of saving the digital signal data internallyin said hand-held device.
 6. The method of claim 5 further including thestep of sending to the user an indication of the subject passing orfailing the test.
 7. The method of claim 4 further including the step oftransferring said digital signal data from said hand-held device to anexternal unit.
 8. An auditory screening device comprising: a hand-heldenclosure; a signal processor within said enclosure; a memory modulewithin said enclosure operatively connected to said signal processor; adisplay screen mounted to said enclosure, said display screen beingoperatively connected to said signal processor; a computer program atleast partial contained in said signal processor, said computer programbeing accessible by a user to perform an otoacoustic emission test andan auditory brainstem response test for a test subject, said memorymodule maintaining a plurality of test subject records for display onsaid display screen; and wherein the otoacoustic auditory emissioninformation is recorded by frames, and information from a precedingframe is used in connection with information of a succeeding frame toreduce the signal to noise level in the received signals.
 9. The deviceof claim 8 wherein the amount of information employed with a succeedingframe is obtained from the formula:$M = {\left( \frac{f_{n}}{f_{s} - 1} \right) \times \left( \frac{f_{s}}{f_{dcl} + 1} \right)}$where M equals overlap number, f_(n) equals frame number, f_(s) equalsframe size and f_(dd) equals frame data cycle length.
 10. The device ofclaim 9 wherein said computer program further includes tympanometry testprocedures conducted independently or in conjunction with otoacousticauditory emission and auditory brainstem response tests.
 11. The deviceof claim 10 wherein the computer program determines data information forthe brainstem response test by counting zero crossings of a sinusoid.12. A method of conducting an auditory test in which a reduced noiseratio is obtained by: receiving auditory signal information in frames;making a determination to accept a frame, reject a frame and update anoise average, or to discard a frame based upon at least one predefinedparameter; and averaging data in a current accepted frame with data fromat least one previous accepted frame, wherein said data from said atleast one previous accepted frame is slid by a predetermined number ofdata points.
 13. A method of conducting an otoacoustic auditory emissiontest in which reduced noise ratio is obtained by: receiving otoacousticauditory emission signal information in frames; overlapping informationfrom a proceeding frame for use in connection with information from asucceeding frame; making a determination to accept the data, to rejectthe data but update a noise average, or to discard the data based uponpredefined parameters; wherein an overlap is determined from theformula:$M = {\left( \frac{f_{n}}{f_{s} - 1} \right) \times \left( \frac{f_{s}}{f_{dcl} + 1} \right)}$where M equals overlap number, f_(n) equals frame number, f_(s) equalsframe size and f_(dd) equals frame data cycle length.
 14. The method ofclaim 13 further including the step of conducting an auditory brainstemresponse test for a test subject.
 15. The method of claim 14 whereindata for the auditory brainstem response test is obtained by countingzero crossings of an internally generated, correlated sinusoid.
 16. Anauditory screening device, comprising: a portable hand-held enclosure; asignal processor housed by said enclosure; at least one input/outputinterface housed by said enclosure and operatively coupled to saidsignal processor; a memory module housed by said enclosure, said memorymodule operatively connected to said signal processor and configured tomaintain at least one test subject record; wherein said signal processoris configured to transmit and receive signals through said at least oneinput/output interface to conduct one or more auditory test proceduresselected from a group comprising otoacoustic emission test procedures,otoreflectance test procedures, auditory brainstem response testprocedures, tympanometry test procedures on a test subject; and whereinsaid signal processor is configured to process otoacoustic emissionsignals received through said input/output interface using an offsetframe overlap method to reduce uncorrelated noise present in resultsassociated with said otoacoustic emissions test procedure.
 17. Theauditory screening device of claim 16 further including: a displayscreen mounted to said enclosure, said display screen being operativelyconnected to said signal processor; and wherein said signal processor isfurther configured to display results associated with a selected testprocedure on said display screen.
 18. The auditory screening device ofclaim 16 wherein said at least one input/output interface is anotoacoustic emission interface, said otoacoustic emission interfaceincluding at least one sound transducer configured to present a varietyof acoustic signals to a test subject ear, and a microphone configuredto receive response acoustic signals from said test subject ear.
 19. Theauditory screening device of claim 18 wherein said otoacoustic emissioninterface is further configured for otoreflectance measurements of atest subject middle ear condition.
 20. The auditory screening device ofclaim 18 wherein said signal processor is further configured with anotoacoustic auditory emission simulator program, whereby said signalprocessor is configured to generate simulated f_(dp) tones in responseto tones generated by said sound transducer.
 21. The auditory screeningdevice of claim 16 wherein said at least one input/output interface isan auditory brainstem interface, said auditory brainstem interfaceincluding at least one sound transducer configured to present anauditory stimulus to a test subject ear, and at least one electrodeconfigured to receive response bioelectrical signals from said testsubject.
 22. The auditory screening device of claim 16 wherein said atleast one input/output interface is a tympanometry interface, saidtympanometry interface including at least one electronic controlchannel, a pump operatively coupled to said electronic control channelfor altering a pressure level in a test subject ear, and a pressuresensor configured to measure said pressure level in said test subjectear.
 23. The auditory screening device of claim 16 wherein said signalprocessor is further configured, for each auditory test procedure, totransmit at least one stimulus signal though said input/outputinterface.
 24. The auditory screening device of claim 16 furtherincluding a display device mounted to said enclosure, said displaydevice being operatively connected to said signal processor, saiddisplay device displaying the results of said one or more selectedauditory test procedures.